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Post by jetjeff on Jan 21, 2017 14:35:19 GMT -5
Hi All, Marking the blade positions on the base disk with a red paint marker and the jig I use to rout out the base disk. The jig has a 3/8" pin that fits into a hole I drilled in the router base. Regards Jeff
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reedy
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Post by reedy on Jan 21, 2017 15:03:44 GMT -5
Hi Jeff Just been watching Homemade Jet engine FD3 scale 2:1 ! don,t listen to me this guys work is not a patch on yours but it runs a treat ,if you watch the video its as per book with the combustor you have made shows you the walking stick mod can,t see how many maybe ten sticks,check the hole pattern does it look as per the book,It starts great on fuel. he shows the NGV with the entry angle,get your carbon wheel built, should be impressive. The compressor wheel has 14 blades looks ok on outside but a bit full in the inlet 7 full 7 half should work well. www.youtube.com/watch?v=L3hZPQT1Nuw
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Post by jetjeff on Jan 21, 2017 16:07:31 GMT -5
Hi Chris,
Yes, I've watched the 2:1 FD3 video many times. The German gentleman did an outstanding job, and yes I stole his idea for the U shaped evaporator tubes. Working on the compressor over the weekend. I have to make a male/female mold for the top cover plate,,,vacuum bagging doesn't deliver enough clamping force to get a compound curved mold to work well.
I plan on making two base disks, one with 90 degree slots and one with 70 degree slots. Slanting the blades forward will present an extra amount of work, but I feel there would be an increase in efficiency in forward slanting them,,,the other plus would be a slightly "longer" bonding area for the blade to disk epoxy joint. Most turbocharger wheels now have slanted blades, so there must be a benefit to this. After I machine the slots I'll mull over which to use.
Regards
Jeff
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Post by Johansson on Jan 21, 2017 16:25:38 GMT -5
Ehum, he is actually a Swede.
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Post by jetjeff on Jan 21, 2017 16:55:43 GMT -5
Hi Anders,
LOL. Wait,,,I know the guy that made the 3D printed engine is a Swede,,,but I thought the guy that made the 2:1 was German. I stand corrected,,,it's all good.
I'm a mongrel,,,1/3 Polish, 1/3 Austrian and 1/3 Czech.
Regards
Jeff
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reedy
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Post by reedy on Jan 22, 2017 4:21:36 GMT -5
HI Jeff
Mongrel is best, I'm always at the vets with my pedigree dog!
Agree with all your ideas about the compressor, worth trying the 70 degree just for the blade hold,thats the beauty of the FD3 you can try ideas out. I've done the curved blade mod on the diffusser vanes hard to tell any difference,you would need to do corrections for temp and pressure before and after mods and have a good running engine with the combustor working will,never done it lots of work.
Make sure you replicate the curve on the base disc,that and the cover what makes the wooden wheel (or carbon)more efficient than the simplified alloy wheel and you can tell the difference with that mod !
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Post by jetjeff on Jan 22, 2017 4:53:41 GMT -5
Hi Chris,
Yep,,,the radius on the curve for the blades is 2" (if you enlarge it 40%), a 1/2 piece of 4" PVC plastic pipe is perfect for the mold.
Not sure why Kurt did a reverse view of the compressor in his plans, other than throw us a curveball,,,lol.
Regards
Jeff
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reedy
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Post by reedy on Jan 22, 2017 4:57:18 GMT -5
Hi Jeff
compressor mod at intake of wheel,mentioned it before.
Just noticed another point Kurt say,s on the drawing ,Do NOT cut the blades back to 62-64 dia people found this reduced the power and did not reduce the temp.Lot of people scraped their wheel.
As long as you have the gap at the tip of the wheel 7.2 size to max 7.5 mm it will not be a problem .
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Post by jetjeff on Jan 22, 2017 5:22:26 GMT -5
Hi Chris,
Somebody made an aluminum Schreckling wheel with cover plate. This may be the wheel that came with the Sneider/Sachez built Schreckling? Try to replicate it out of carbon.
Regards
Jeff
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Post by jetjeff on Jan 22, 2017 10:44:03 GMT -5
Hi All, I've laid out the blade slot positions and made a jig to mill out the slots with a .046" end mill. Part of the problem with my 1st carbon compressor was the blade slots were too tight, wiping most of the epoxy off the blades as they were inserted in the base disk. You can tell from the pic, the slots are at a much shallower angle. Regards Jeff
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reedy
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Post by reedy on Jan 22, 2017 14:49:34 GMT -5
Hi Jeff Going to just throw this idea out there ! years ago i had the idea of making a wooden wheel as a mold tool, you only need the inside shape, no stepping on the back or carbon banding,make it so the top can come off,then get something called rose metal (low melting point alloy ) which has a melting point of 94 to 98 c does not contract when cold. Pour melt alloy into the wooden wheel,when cold take out and you have an intensifier for molding the blades round it would need more tooling making perhaps cut them into separate blocks to wrap the carbon round then assemble with a jubilee clip on the outside and plates top ad bottom with carbon on clamped or bolted together,top and bottom plate is lined up with a boss same size as intake.when epoxy has set put in boiling water to remove the intensifier. Only a rough daft of the idea, would need a lot of thinking about and trail and error. www.zilt.co.uk/LowMelting/RoseMetal.htmlmay be a way of making an intensifier for you top plate or the blades,you can use plastercine as a dam when molding the metal. Worth looking at the other alloys bend alloy for tube bending
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reedy
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Posts: 111
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Post by reedy on Jan 22, 2017 15:02:07 GMT -5
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Post by jetjeff on Jan 22, 2017 16:54:04 GMT -5
Hi Chris, Thanks for the pics,,,awesome. I completed cutting the slots on the 90 degree base disk. Now comes the 75 degree version. I've indexed the head of my Bridgeport to 15 degrees (20 seemed too radical). I never seem to get as much done in a weekend as I'd hoped. I broke two end mills making the 90 degree version, end mills this size are as fragile as glass. Regards Jeff
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reedy
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Post by reedy on Jan 22, 2017 18:00:06 GMT -5
Hi Jeff
I am amazed you only snapped two! drilling one hole with a 1mm drill is my limit. Another idea for molding your blades ,cut through a plate thickness of tallest part of blade with a 2" rad put half thicknes of cloth you use for blade on each half of tool bend 90 degree around to base clamp it together to form blade shape and clamp down on another plate to form at blade 1mm thick with 0.5 flange T shape. cut the T base so it forms segments like an orange do 10 more ,then push them through your sloted plate with epoxy on, then another solid disc to cover up ,when glued fit top like you normally do through a slotted top plate trim blades flush then glue another layer of cloth to tie the slots together. I will do a drawing if that does not make sense,but that should be very strong,never bend the blade over with a T base and a solid disc below with no slots to weaken it.the blade will be very solid fully consolidated. You only need one slotted base disc,and one unslotted
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Post by racket on Jan 22, 2017 18:38:12 GMT -5
Hi Guys
Have you looked at the Atlascopco closed impellers as used in their large industrial cetrif. compressors ,for ideas , ....... some very nice gear :-)
Cheers John
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